Napoli’s first spring training with the Red Sox was defined with uncertainty after it was discovered he had a degenerative condition in his hips. The team held him out of the first seven Grapefruit League games as a precaution and limited how often he was allowed to run.

The diagnosis, which came after Napoli agreed to a three-year, $39 million deal, caused the Red Sox to renegotiate him down to a one-year, $5 million agreement that included $8 million in incentives based on playing time.

Napoli also was restricted to playing first base. He wasn’t even the emergency catcher — that’s how strict the rules were. Nobody could say for certain how often he would be able to play.

“The funny thing was that I felt fine,” Napoli said Friday. “I knew what the doctors were saying and I believed them. But I knew I could play.”

Now Napoli is going through spring training free of the microscope. The daily questions about how he feels and his transition to first base have ended. He’s far more noted for his bushy beard than his faulty hips.

The only question Napoli has on his mind now is how much better he can be than last season. He wants to be an All-Star first baseman.

“I think I can be a lot better,” he said. “You never want to stop improving. I feel very comfortable here now. I feel like I can do more.”

Napoli has worked on refining his two-strike approach after setting a team record with 187 strikeouts last season. His willingness to work deep into the count leads to a lot of strikeouts but Napoli believes he can put the ball in play more often without sacrificing power.

He also wants to become better at first base. Kansas City’s Eric Hosmer won the Gold Glove last season, but advanced defensive statistics showed Napoli was the best defensive first baseman in the American League.

His footwork, range, and arm accuracy were all better than the Red Sox expected.

“I don’t miss catching. I love playing first,” Napoli said. “[Infield coach Brian Butterfield] and I have a good relationship. We talk all the time about little things or decisions I made. He can just look at me and point and I know what he’s talking about.”

With rookie Xander Bogaerts at shortstop and the still-developing Will Middlebrooks at third base, Napoli’s play at first is important to the team’s stability.

“I think he will be better,” manager John Farrell said. “The work that Butter’s done with him, the athleticism that Mike shows, he’s got soft hands. A full year under his belt at the position just adds for greater comfort. He’s turned himself into a hell of a first baseman.

Said Napoli: “The guys made it easy for me last season. I want Xander and Will to know that if they get the throw there, I’ll make the play whether I have to come off the bag or do whatever. They should have faith in me.”

Napoli’s hip condition, avascular necrosis, has been controlled by medication. Doctors use an MRI to check his status every three months but have found no spread of the disease.

“We’ll monitor it,” said Farrell. “But it’s not something that’s a focal point with how he’s feeling. We’ll go through the same steps that were in place last year as far as making sure there’s been no advancement of the condition.

“There’s no extra attention for health reasons. I know he feels much better about himself for the obvious reasons and physically he feels great.”

On Friday, Napoli volunteered to take a 2½-hour bus ride to get three at-bats against the Blue Jays because he wanted to play back-to-back days.

“I feel normal again,” Napoli said. “It’s just getting ready for the season like usual and not having to worry about anything. That should really help me.”